T-Mobile NAT64 IPv6 Prefixes


    T-Mobile defaults to IPv6 on iOS devices, and I have found that for certain internet destinations in Safari, connections will only be successful if a NAT64 mapped version of the IPv4 address is used.


    My question is: what are the IPv6 NAT64 prefixes within T-Mobile's network? Is there just one or are there potentially multiple?


    I have observed that 2607:7700::1f:0:1: is a valid NAT64 prefix for my iPhone now and using that results in my phone connecting successfully, but will this prefix work nationwide? Is there a list of NAT64 prefixes available if there are more than one prefix, or is there a mechanism other than RFC 7225 that T-Mobile offers for discovery of the prefix? (as DNS lookups cannot be performed in client JavaScript).


    Thanks very much for the assistance.

      All replies

      • dragon1562

        Re: T-Mobile NAT64 IPv6 Prefixes

        It is more accurate to say that Apple defaults to IPv6 and removed it from  the user to change to a IPv4 connection. If you need to connect to say a sercurity video feed that uses IPv4 you will need a android device since it allows you to create a new APN to force a IPv4 connection. You can also use a VPN.

          • aaronjbarlow

            Re: T-Mobile NAT64 IPv6 Prefixes

            Apple says "You can only edit or view your APN if your carrier allows it", and it appears from talk on Apple forums that T-Mobile's carrier settings remove the ability to change the APN. However, that's not the core of my question.


            We can successfully connect to IPv6 addresses on TMobile with Mobile Safari if and only if the NAT64-mapped IPv4 address is used. Hence, as a workaround it would be useful to know what NAT64 prefixes might be in use so that I can populate a list using those.